In a medium sized bowl whisk together the brown sugar, eggs, vanilla extract and mashed banana.

Add the cooking oil to the brown sugar mixture and stir to combine.

In another large bowl combine the flour nd cinnamon. Gently fold in the berries, making sure they are coated with flour. This helps to prevent the berries from sinking during baking.

Add the wet ingredients to the dry ingredients and stir only until the ingredients are just combined. Do not over mix the batter or tough muffins will result.

Divide the batter evenly among the 12 muffin cups, using two spoons or an ice cream scoop. I used ice crean scoop, for this size cups it just about the right amount of batter using the ice cream scoop and much much easier to work with..

Place in the oven and bake until a tester inserted in the center of a muffin comes out clean, 20 to 25 minutes. Transfer to a wire rack to cool